Imo000

But that's it.....yours didn't and my project '99 996, that has 200K miles has a stock, double row bearing. I'm planning on changing it to the LN unit and wanted to know what to expect from it. If they are as robust as claimed above, this should be the last bearing this engine will ever need.

D6lc

Jake,

I am not trying to be confrontational but you don't seem to have answered the original question, how long does the bearing last, or what is the recommended replacement mileage?
My gearbox is out and I'm considering the LN but like the OP woul like a clear guide on its life

FabianS

So if someone say purchased a 99-01 996 and put in the LN dual row bearing that would be considered the "fix" for the IMS issue? I'm looking at 996's and although I prefer the 2002 plus headlights, I would prefer reliability over style.

MiamiC70

My original question is I put an LN bearing in car at 32k miles not about ready to do 60k and clutch so will have transmission / engine separated should I be thinking well might as well replace bearing again? I mean does not really make sense to put in a new LN bearing again down the road and have to consider again separating transmission / engine just for that.

carcster88

Great post. Looks like I will be fine with my new dual row LN IMS bearing fix.

Also, my dealer out here was very familiar with it and they recommend the fix to 996 owners when they have the clutch replaced. I have a good dealer though that treats me like gold. That is nice for a change.

JMLavoie

I have a 00 C2, like you, carcster88, with the last 4 VIN digits being ... 0220.
Do this mean that I have a dual-row IMS bearing as you originally had before your replacement?
My car has 140k kms on it but I know of someone with a 99 C4 whose IMSb blew his engine at 160k kms. These IMSb blow-outs are very erratic, indeed!
Martin

Imo000

There is only one way to be 100% sure. Have to look at the flange.

BruceP

I'm pretty sure the answer is yes. Mine ends in 2351, and I had the dual row bearing.

Palmbeacher

On the one hand you've only got 28K miles on the bearing. It really should not need replacing, especially if you've changed oil frequently. Despite Jake's well-intentioned assertion that the small bearing is inadequate, the engineering facts are that the cam tensioning should be equal and cancel out, thereby the bearing should have little or no radial/lateral loading. Likewise if the IMS shaft is lined-up with the bearing spindle and bolt and the bearing runs true, it really oughtn't be under much if any load. I'm sure Porsche's engineers calculated the expected load and specified a bearing capable of enduring it. However they may have chosen one that is quite near the edge the envelope, thus if there are other factors out of tolerance that do increase the load it could prove too much for the bearing.

My personal opinion based on knowledge of engineering is that the greatest likelihood as to why a number of the small single-race LN bearings have failed comes down to incompetent installation protocols or what in medicine is referred-to as improper case selection, eg installing a new bearing in an engine with preexisting damage or debris.

That said, since you will be undertaking the labour anyway, it seems sensible to change the bearing, assuming whoever is doing the job is at least as competent as whomever installed the last one.

I'm in a slightly different boat, in that I had my clutch and the LN bearing done 9000 miles ago, which for me represents 1,5 years of (daily) driving. I've got 4,5 years remaining on my extended warranty, whereupon the bearing (and clutch) will have a total of only 36,000 miles. Terms of my warranty mandate I change oil every 5K miles or 6 months, which in my case works out to an oil service every 3K miles. So I'm not even thinking about touching the LN bearing until the warranty expires. If I should decide to keep the car after that point (it will be 12 years old by then) I'll revisit the issue.

There's only so much money I'd want to throw at that bearing, given that as the miles mount so does the possibility of one of the other catastrophic failure modes claiming the engine.

BED997

Subscribed. Keep us posted please.

carcster88

You should have dual row as well. When I had my upgrade done at the dealer, they did order both the single and dual row just in case. Mine was dual. At least I got lucky somewhere....LOL.

street rod

Its my understanding that all 1999 cars got the dual row, and in the 2000 and 2001 its a crap shoot. You could have the single or the dual and need to take a look in order to be sure.

BruceP

I may be wrong, but I didn't think they went back and forth between two rows and one row. I thought the changeover was a mid-year event. IIRC, when I had my dual row replaced, the VIN was how LN could confirm the dual row was correct. The previous poster's VIN suggested his car was built prior to mine.

street rod

Ok maybe so but if thats the case I wonder why they went back to the single row when building some of the 2001 cars?

BruceP

Common confusion, because it seems so counter-intuitive... the early M96s got dual row bearings, and Porsche switched from dual to single row, for some reason. Early cars, dual. Later cars, single.